Vibration screening: A detailed study using image analysis techniques to characterize the bed behavior in solid–liquid separation

Abstract

Particulate suspensions systems are present in various industrial sectors, vibrating screens being some of the most versatile pieces of equipment for the separation of these two phases. This paper presents a study of the dynamics of the mixture on the screen during solid–liquid separation using vibration screening. The independent variables studied were g-force, volumetric concentration of solids in the feed, feed flow rate and inclination of the screen. The equipment used was a vibrating screen of 175 mesh with 95 μm aperture size. The evaluated response variables were the residual moisture content of the retained solids, the screen area occupied by the liquid, the transport velocity of the retained solids and the screen area occupied by the retained solids. The solid material used was sand with a density of 2.67 g/cm3 and a Sauter mean diameter of 373 μm, and the liquid phase was composed of water containing 0.1% xanthan gum. A central composite design was applied to the experiments and the results for each response were analyzed statistically. It was possible to verify that the increase in the g-force and screen inclination variables increased the operational capacity, since the areas occupied by the liquid and the retained solids were reduced. It was also found that higher volumetric concentrations of solids in the feed favored a reduction in the moisture content of the retained solids and their transport on the screen, since larger particulate material conglomerates were formed, which had a more uniform displacement path.